1. Field of the Invention
The present invention relates to an optical fiber array having a holding member mounted thereto, and having optical fibers arranged and held within predetermined intervals. More particularly, the present invention relates to a technique of preventing release or delamination of the holding member.
2. Description of Related Art
Conventionally, a fiber array having optical fibers arranged therein and fixed thereto is formed as shown in FIG. 4. In FIG. 4, reference numeral 12 denotes a holding member that consists of a substrate 13 and a cover plate 15. A plurality of V grooves 14 having a V shaped section (housing grooves) are formed on the substrate. Optical fibers (optical fiber bare portions) 1 are housed in the individual V grooves 14, and an adhesive is filled in the V grooves. Then, the cover plate 15 is positioned on the V grooves to pinch the optical fibers 1 between substrate 13 and cover plate 15. In this manner, the optical fibers 1 are adhered and fixed in the V grooves 14. In addition, reference numeral 1a denotes a covered portion of the optical fibers, where a plurality of the optical fibers 1a are coupled to one another via a covering to form a fiber ribbon 16.
The holding member 12 is formed by processing a glass plate, for example, with the V grooves 14 being formed in parallel on a substrate top which is ground to a mirror face. In addition, a space between adjacent V grooves is small so that an adhesive face is widely formed at the right and left ends of a bundle of the V grooves in order to ensure adhesion between the substrate 13 and the cover plate 15.
However, the above described fiber array is often placed under severe outdoor environments. That is, the fiber array is subject to temperatures ranging from a high temperature of 60° C. to a low temperature of −40° C. Fiber arrays are also subjected to dry, humid and high temperature environments such as desert conditions or the like. The optical fiber array is required to maintain constant and proper performance characteristics under such severe environments for long durations. However, in the case where the above fiber array is subjected to such severe environmental conditions for long durations, there has occurred a phenomenon that the substrate 13 and the cover plate 15 fixing the optical fibers 1 in the V grooves are released or delaminated due to environmental variations over time. This results in the optical fibers being unreliably fixed in the V grooves.
In an optical fiber array, if an optical axis deviates from a predetermined position, an optical transmission loss is increased between this optical fiber and optical part being optically connected therewith. Thus, a very high position precision of 0.5 microns or less is required to maintain the optical connection. If the above release phenomenon occurs, a displacement of the optical fiber occurs, resulting in degraded optical transmission characteristics. In addition, an optical fiber may become detached from the substrate housing the fiber.